#!/usr/bin/env bash

################################################################################
# Runs pylint on changed files using a preconfigured .pylintrc file.
#
# Usage:
#     check/pylint-changed-files [BASE_REVISION]
#
# You can specify a base git revision to compare against (i.e. to use when
# determining whether or not a line is considered to have "changed"). To make
# the tool more consistent, it actually diffs against the most recent common
# ancestor of the specified id and HEAD. So if you choose 'origin/master' you're
# actually diffing against the output of 'git merge-base origin/master HEAD'.
#
# If you don't specify a base revision, the following defaults will be tried,
# in order, until one exists:
#
#     1. upstream/master
#     2. origin/master
#     3. master
#
# If none exists, the script fails.
#
# See check/pylint for linting all files.
################################################################################

# Get the working directory to the repo root.
cd "$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
cd "$(git rev-parse --show-toplevel)"

# Figure out which revision to compare against.
if [ ! -z "$1" ] && [[ $1 != -* ]]; then
    if [ "$(git cat-file -t $1 2> /dev/null)" != "commit" ]; then
        echo -e "\033[31mNo revision '$1'.\033[0m" >&2
        exit 1
    fi
    rev=$1
elif [ "$(git cat-file -t upstream/master 2> /dev/null)" == "commit" ]; then
    rev=upstream/master
elif [ "$(git cat-file -t origin/master 2> /dev/null)" == "commit" ]; then
    rev=origin/master
elif [ "$(git cat-file -t master 2> /dev/null)" == "commit" ]; then
    rev=master
else
    echo -e "\033[31mNo default revision found to compare against. Argument #1 must be what to diff against (e.g. 'origin/master' or 'HEAD~1').\033[0m" >&2
    exit 1
fi
base="$(git merge-base ${rev} HEAD)"
if [ "$(git rev-parse ${rev})" == "${base}" ]; then
    echo -e "Comparing against revision '${rev}'." >&2
else
    echo -e "Comparing against revision '${rev}' (merge base ${base})." >&2
    rev="${base}"
fi

changed=$(git diff --name-only ${rev} -- \
    | grep -E "^(cirq|dev_tools|examples).*.py$"
)

num_changed=$(echo -e "${changed[@]}" | wc -w)

# Run it.
echo "Found ${num_changed} lintable files associated with changes." >&2
if [ "${num_changed}" -eq 0 ]; then
    exit 0
fi
pylint --rcfile=dev_tools/conf/.pylintrc ${changed[@]}

